Fatal error: Call to a member function get_extra_permastruct() on a non-object i

how can i fix this

Try uploading a fresh copy of the WordPress files (excluding the folder wp-content).

in my C panel ?

From your CPanel or FTP file manager, upload and replace WordPress file with sub-folders excluding the wp-content folder.

Was there a solution found for this? I’m experiencing the same error when calling:

$args = array(						'number'                    => 45,
						'echo'                      => false,
						'format'                    => 'array',
						'taxonomy'                  => 'category',
);
$categories=wp_tag_cloud($args);

A possible scenario: get_extra_permastruct, get_post_permalink or get_permalink called too early.
For example, it was called on plugins_loaded hook.

Calling it in init hook, or later (wp_loaded) should solve the problem.